Many houses and other buildings use warm air furnaces to provide heat. Generally, these furnaces operate by heating air received through cold air or return ducts and distributing the heated air throughout the building using warm air or supply ducts. A circulation fan directs the cold air into a heat exchanger, which may be composed of metal. The heat exchanger metal is heated using a burner that burns fossil fuels. The burner is ignited with an ignition device, such as an AC hot surface ignition element. The air is heated as it passes by the hot metal surfaces of the heat exchanger. After the air is heated in the heat exchanger, the fan moves the heated air through the warm air ducts. A combustion air blower, or inducer, is used to remove exhaust gases from the building.
Warm air furnaces can be complex and costly to both manufacture and assemble. One reason for this complexity and high cost is the large number of components used in a warm air furnace. As a result of the large number of components, warm air furnaces can breakdown and become unreliable. Such unreliability can also result in unsafe operating conditions, which can be particularly harmful since a fuel (e.g., natural, propane or  butane gas) is typically utilized in a warm air furnace. Because furnaces play a critical role in the comfort of the occupants of the building, it is also important that the warm air furnace remains functional and provides efficient heat.
Therefore, it is desirable to provide a reduced-cost warm air furnace that improves on the reliability, functionality, and safety of prior art warm air furnaces. 